The present invention relates to a double check valve assembly and an arrangement for testing the double check valve assembly. More specifically, the present invention is directed toward a double check valve assembly for providing back-flow prevention in a fire suppression system and an arrangement for testing a double check valve assembly for providing back-flow prevention in a fire suppression system and for testing the fire suppression system.
Double check valve systems and methods of testing those systems are well known. In addition, the use of double check valve systems in a fire suppression system is also well known to provide back-flow protection. These known systems are designed to prevent a reverse flow in water lines and to prevent non-potable water from entering a safe drinking water system.
Double check valve systems for use in fire suppression systems come in a variety of shapes and sizes and in a variety of different materials. For example, double check valve systems may be of bronze or iron or even stainless steel. Typical systems include the Series 007 and Series 775 Double Check Valve Assemblies of Watts Regulator Company, North Andover, Mass. Other typical systems are available from Conbraco, Febco, and Zurn/Wilkins as well as from other manufacturers.
The typical double check valve systems all include a first shut off valve, two independently acting, spring loaded check valves, and a second shut off valve with four test cocks provided for the double check valve system. The double check valve assemblies can be installed vertically or horizontally and typically have ball type test cocks. The shut-off valves may be of various types such as quarter-turn, full port bronze ball valve shut off valves. In the normal configuration, each check valve maintains a minimum pressure drop of 1 PSI across the valve during normal operation. In the event that the pressure downstream of the assembly rises above the supply pressure, both of the check valves are designed to close to prevent a backflow into the supply line.
If desired, the double check valve assembly may also be provided with a reduced pressure zone (xe2x80x9cRPZxe2x80x9d) valve which includes a hydraulically dependent, mechanically independent pressure differential relief valve located in the zone between the two check valves. The relief valve operates on a differential pressure. Supply pressure on the upstream side of the first check valve acts to close the relief valve in normal operation. If the system should have a back-pressure, the relief valve opens to maintain the pressure in the reduced pressure zone about 3 PSI less than the inlet pressure.
In addition, the double check valve assembly may be provided with bypass piping including a bypass line assembly including a water meter in series with the double check valve. In a typical arrangement all flow up to about 5 gallons per minute (GPM) occurs through the bypass piping. Flow above 5 GPM causes the check valves in the main line to open and flow occurs both through the main line as well as through the bypass piping.
In fire suppression systems, especially such systems for use in residential housing, the need exists to provide an efficient and relatively inexpensive check valve arrangement for preventing a backflow into the potable water system as well as an arrangement for testing the system.
The present invention solves the foregoing problems, and provides additional advantages, by providing a double check valve assembly in which a test port which is provided downstream of the second check valve is provided with a three way valve (such as a 3-way globe valve with a side outlet) having one inlet and two outlets with the valve permitting communication between the inlet and both outlets in one configuration and blocking communication between the inlet and both outlets in another configuration. One of the outlets of the three way valve is provided with a pressure gauge and the other of the outlets is normally closed by a plug but may serve as a test cock.
In a more preferred embodiment of the present invention, both the test port which is provided downstream of the second check valve as well as the test port which is provided between the first and second check valves is provided with a three way valve (such as a 3-way globe valve with a side outlet). One of the outlets of the second three way valve is provided with a pressure gauge and the other of the outlets is normally closed by a plug but may serve as a test cock.
In other embodiments of the present invention, the double check valve assembly may be provided with a flow detector arrangement for indicating that a flow has occurred through the back flow prevention arrangement. The flow detector may indicate that the second check valve is open or may indicate that a flow has occurred through the second check valve. Preferably, an alarm is provided for indicating that a flow has occurred, with a time controller provided to provide a time delay to prevent false alarms. The time controller is preferably battery powered with an automatic dialer provided to call a predetermined number such as a fire department or burglar alarm company in response to an indication that a flow has occurred through the double check valve assembly. The alarm, the time delay, and the automatic dialer circuitry are all preferably battery powered but can be powered by house current or conventional power lines, if desired.
The arrangement may be provided, if desired, with an arrangement for preventing a rapid closing of the shut off valves and with an arrangement for indicating the state of the shut off valves or that someone has tampered with the shut off valves.
In addition, a test and drain valve arrangement may be provided downstream of the second check valve to selectively permit a flow through the double check valve arrangement corresponding to the flow through a single sprinkler head when the valve is in a test configuration and selectively permitting the back flow arrangement to be drained when the valve is in a drain configuration.
In the present invention, a fire suppression system is also disclosed having a conduit with a flow switch, the conduit supplying fluid to a plurality of sprinkler heads, with the flow switch being battery powered, preferably independent of any line current.
In addition, the system further comprises an automatic dialer for calling a predetermined number in response to a signal from the flow switch with the automatic dialer being provided at the flow switch and preferably being battery powered independent of any line current